ALEC · Alector, Inc. · Insider Trading

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.495 to $2.52. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.49 to $2.75. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.49 to $2.75. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.49 to $2.75. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The reported securities are held directly by The Rosenthal Family Revocable Trust Dated November 4, 1994, as restated on June 9, 1999, for which the Reporting Person serves as trustee.

The reported securities are held directly by the Adi Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

The reported securities are held directly by the Shani Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

The reported securities are held directly by the Noam Rosenthal 2007 Trust dated March 27, 2007, for which the Reporting Person serves as trustee.

The reported shares are represented by restricted stock units, or RSUs, which vest in 12 equal quarterly installments beginning on September 1, 2026.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 16, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The reported shares are represented by restricted stock units, or RSUs, which vest on the earlier of (i) June 17, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders.

The shares subject to the option vest in 12 equal monthly installments beginning on July 17, 2026, provided that the shares subject to the option will vest in full on the earlier of the one-year anniversary of the date of grant or the date of the Issuer's next annual meeting of stockholders.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.86 to $1.94. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.92 to $2.08. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.92 to $2.08. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.92 to $2.08. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares are represented by restricted stock units, or RSUs, which vest in 4 equal quarterly installments beginning on June 1, 2026.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The reported shares are represented by restricted stock units, or RSUs, one half (1/2) of the total shares shall vest on September 1, 2026 and one half (1/2th) of the total shares shall vest on March 1, 2027.

The reported shares are represented by restricted stock units, or RSUs, one half (1/2) of the total shares shall vest on September 1, 2026 and one half (1/2th) of the total shares shall vest on March 1, 2027.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.06 to $2.12. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.04 to $2.37. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.04 to $2.37. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.04 to $2.37. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 5, 2025.

The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 5, 2025.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.095 to $1.14. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.095 to $1.14. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.095 to $1.14. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $1.095 to $1.14. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.

The reported shares are represented by restricted stock units, or RSUs, which vest in 12 equal quarterly installments beginning on December 1, 2025.

Shares subject to the option vest in 48 equal monthly installments beginning on December 10, 2025.

Shares subject to the option vest in 48 equal monthly installments beginning on December 10, 2025.

The reported shares are represented by restricted stock units, or RSUs, which vest in 12 equal quarterly installments beginning on December 1, 2025.

Shares subject to the option vest in 48 equal monthly installments beginning on December 10, 2025.

The reported shares are represented by restricted stock units, or RSUs, which vest in 12 equal quarterly installments beginning on December 1, 2025.

The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $2.30 to $2.59. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff, the issuer, or any security holder of the issuer upon request.